I. Biogeochemical cycles
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Transcript of I. Biogeochemical cycles
I. Biogeochemical cyclesI. Biogeochemical cycles
The Carbon Cycle The Carbon Cycle
A. The carbon cycleA. The carbon cyclei. The global movement of carbon between organisms i. The global movement of carbon between organisms and the abiotic environment is known as the carbon and the abiotic environment is known as the carbon cyclecycleCarbon is present in the atmosphere as carbon Carbon is present in the atmosphere as carbon dioxide(CO2), the ocean as carbonate and bicarbonate dioxide(CO2), the ocean as carbonate and bicarbonate (CO32-, HCO3-) and sedimentary rock as calcium (CO32-, HCO3-) and sedimentary rock as calcium carbonate (CaCO3)carbonate (CaCO3)2. Proteins, carbohydrates, and other molecules 2. Proteins, carbohydrates, and other molecules essential to life contain carbonessential to life contain carbonCarbon makes up approximately 0.04% of the Carbon makes up approximately 0.04% of the atmosphere as a gas atmosphere as a gas
The Carbon CycleThe Carbon Cycleii. Carbon primarily cycles through both biotic and abiotic ii. Carbon primarily cycles through both biotic and abiotic environments via photosynthesis, cellular respiration and environments via photosynthesis, cellular respiration and combustion (CO2)combustion (CO2)1. Photosynthesis incorporates carbon from the abiotic 1. Photosynthesis incorporates carbon from the abiotic environment (CO2) into the biological compounds of environment (CO2) into the biological compounds of producers (sugars)producers (sugars)2. Producers, consumers and decomposers use sugars 2. Producers, consumers and decomposers use sugars as fuel and return CO2 to the atmosphere in a process as fuel and return CO2 to the atmosphere in a process called cellular respirationcalled cellular respiration3. Carbon present in wood and fossil fuels (coal, oil, 3. Carbon present in wood and fossil fuels (coal, oil, natural gas) is returned to the atmosphere by the natural gas) is returned to the atmosphere by the process of combustion (burning)process of combustion (burning)The carbon-silicate cycle (which occurs on a geological The carbon-silicate cycle (which occurs on a geological timescale involving millions of years) returns CO2 to the timescale involving millions of years) returns CO2 to the atmosphere through volcanic eruptions and both atmosphere through volcanic eruptions and both chemical and physical weathering processes chemical and physical weathering processes
The Nitrogen CycleThe Nitrogen Cyclei. i. The global circulation of nitrogen between The global circulation of nitrogen between
organisms and the abiotic environment is organisms and the abiotic environment is know as the nitrogen cycleknow as the nitrogen cycle
1.1. Atmospheric nitrogen (N2) is so stable that it must Atmospheric nitrogen (N2) is so stable that it must first be broken apart in a series of steps before it first be broken apart in a series of steps before it can combine with other elements to form can combine with other elements to form biological moleculesbiological molecules
2.2. Nitrogen is an essential part of proteins and Nitrogen is an essential part of proteins and nucleic acids (DNA)nucleic acids (DNA)
3.3. The atmosphere is 78% nitrogen gas (N2)The atmosphere is 78% nitrogen gas (N2)
Five steps of the nitrogen cycleFive steps of the nitrogen cycle
1.1. Nitrogen fixation Nitrogen fixation
2.2. Nitrification Nitrification
3.3. Assimilation Assimilation
4.4. Ammonification Ammonification
5.5. Denitrification Denitrification
The Nitrogen CycleThe Nitrogen Cycle
1. Nitrogen fixation1. Nitrogen fixationa.a. Conversion of gaseous nitrogen (NConversion of gaseous nitrogen (N22) to ) to
ammonia (NHammonia (NH33))
b.b. Nitrogen-fixing bacteria (including Nitrogen-fixing bacteria (including cyanobacteria) fixes nitrogen in soil and cyanobacteria) fixes nitrogen in soil and aquatic environments (anaerobic process)aquatic environments (anaerobic process)
c.c. Combustion, volcanic action, lightning Combustion, volcanic action, lightning discharges, and industrial processes also fix discharges, and industrial processes also fix nitrogennitrogen
The Nitrogen CycleThe Nitrogen Cycle
2. Nitrification2. Nitrification
a. Conversion of ammonia (NH3) or a. Conversion of ammonia (NH3) or ammonium (NH4+) to nitrate (NO3-)ammonium (NH4+) to nitrate (NO3-)
b. Soil bacteria perform nitrification in a b. Soil bacteria perform nitrification in a two-step process (NH3 or NH4+ is two-step process (NH3 or NH4+ is converted to nitrite (NO2-) then to NO3-)converted to nitrite (NO2-) then to NO3-)
c. Nitrifying bacteria is used in this processc. Nitrifying bacteria is used in this process
The Nitrogen CycleThe Nitrogen Cycle
3. Assimilation 3. Assimilation a. Plant roots absorb NOa. Plant roots absorb NO3-3-, NO, NO33 or NO or NO4+4+ and assimilate the nitrogen of these and assimilate the nitrogen of these molecules into plant proteins and nucleic molecules into plant proteins and nucleic acidsacidsb. Animals assimilate nitrogen by b. Animals assimilate nitrogen by consuming plant tissues (conversion of consuming plant tissues (conversion of aminio acids to proteins)aminio acids to proteins)c. This step does not involve bacteriac. This step does not involve bacteria
The Nitrogen CycleThe Nitrogen Cycle
4. Ammonification4. Ammonification
a. Conversion of biological nitrogen compounds a. Conversion of biological nitrogen compounds into NH3 and NH4+into NH3 and NH4+
b. NH3 is released into the abiotic environment b. NH3 is released into the abiotic environment through the decomposition of nitrogen-through the decomposition of nitrogen-containing waste products such as urea and uric containing waste products such as urea and uric acid (birds), as well as the nitrogen compounds acid (birds), as well as the nitrogen compounds that occur in dead organisms that occur in dead organisms
c. Ammonifying bacteria is used in this processc. Ammonifying bacteria is used in this process
The Nitrogen CycleThe Nitrogen Cycle
5. Denitrification 5. Denitrification
a. Reduction of NO3- to N2a. Reduction of NO3- to N2
b. Anaerobic denitrifying bacteria reverse b. Anaerobic denitrifying bacteria reverse the action of nitrogen-fixing and nitrifying the action of nitrogen-fixing and nitrifying bacteriabacteria
Nitrogen CycleNitrogen Cycle
How to Remember the PartsHow to Remember the Parts FixNAAD ANPAN
Process
Fix- nitrogen fixation
Nitrification
Assimilation
Ammonification
Denitrification
Product
Ammonia
Nitrates
Proteins
Ammonia
Nitrogen
The phosphorus cycleThe phosphorus cycle
C. The phosphorus cycleC. The phosphorus cyclei. Phosphorus cycles from land to sediments in the i. Phosphorus cycles from land to sediments in the ocean and back to landocean and back to land
1. Phosphorus erodes from rock as inorganic 1. Phosphorus erodes from rock as inorganic phosphates and plants absorb it from the soilphosphates and plants absorb it from the soil
2. Animals obtain phosphorus from their diets, 2. Animals obtain phosphorus from their diets, and and decomposers release inorganic phosphate into decomposers release inorganic phosphate into the the environmentenvironmentii. Once in cells, phosphates are incorporated into ii. Once in cells, phosphates are incorporated into biological molecules such as nucleic acids and ATP biological molecules such as nucleic acids and ATP (adenosine triphosphate)(adenosine triphosphate)iii. This cycle has no biologically important gaseous iii. This cycle has no biologically important gaseous compoundscompounds
The sulfur cycleThe sulfur cycle
D. The sulfur cycleD. The sulfur cycle
i. Most sulfur is underground in sedimentary i. Most sulfur is underground in sedimentary rocks and minerals or dissolved in the oceanrocks and minerals or dissolved in the ocean
ii. Sulfur gases enter the atmosphere from ii. Sulfur gases enter the atmosphere from natural sources in both ocean and landnatural sources in both ocean and land
1. Sea spray, forest fires and dust storms 1. Sea spray, forest fires and dust storms deliver sulfates (SOdeliver sulfates (SO44
2-2-) into the air) into the air
2. Volcanoes release both hydrogen 2. Volcanoes release both hydrogen sulfide sulfide (H(H22S) and sulfur oxides (SOS) and sulfur oxides (SOxx) )
The sulfur cycleThe sulfur cycle
iii. A tiny fraction of global sulfur is present in living iii. A tiny fraction of global sulfur is present in living organismsorganisms
1. Sulfur is an essential component of proteins1. Sulfur is an essential component of proteins
2. Plant roots absorb SO2. Plant roots absorb SO442-2- and assimilate it by and assimilate it by
incorporating the sulfur into plant proteinsincorporating the sulfur into plant proteins
3. Animals assimilate sulfur when they 3. Animals assimilate sulfur when they consume plant proteins and covert them to consume plant proteins and covert them to animal proteinsanimal proteins
iv. Bacteria drive the sulfur cycleiv. Bacteria drive the sulfur cycle
The hydrologic cycle The hydrologic cycle
i. The hydrologic cycle is the global i. The hydrologic cycle is the global circulation of water for the environment circulation of water for the environment to living organisms and back to the to living organisms and back to the environmentenvironment
1. It provides a renewable supply of purified 1. It provides a renewable supply of purified water for terrestrial organismswater for terrestrial organisms
2. the hydrologic cylce results in a balance 2. the hydrologic cylce results in a balance between water in the ocean, on the land, between water in the ocean, on the land, and in the atmosphereand in the atmosphere
The hydrologic cycle The hydrologic cycle
ii. Water moves from the atmosphere to the ii. Water moves from the atmosphere to the land and ocean in the form of land and ocean in the form of precipitationprecipitation
iii. Water enters the atmosphere by iii. Water enters the atmosphere by evaporation and transpirationevaporation and transpiration
iv. The volume of water entering the iv. The volume of water entering the atmosphere each year is about 389,500 atmosphere each year is about 389,500 km3km3
The hydrologic cycle The hydrologic cycle
Math Question: Based on the amount of Math Question: Based on the amount of water that enters the atmosphere annually. water that enters the atmosphere annually. How much water enters the atmosphere How much water enters the atmosphere daily? Show all work and remember units. daily? Show all work and remember units.
Solar Radiation Solar Radiation
A. The sun powers biogeochemical cycles A. The sun powers biogeochemical cycles (i.e., hydrologic, carbon) and is the primary (i.e., hydrologic, carbon) and is the primary determinant of climate determinant of climate
B. Most of our fuels (i.e., wood, oil, coal, B. Most of our fuels (i.e., wood, oil, coal, and natural gas) represent solar energy and natural gas) represent solar energy captured by photosynthetic organismscaptured by photosynthetic organisms
Solar Radiation Solar Radiation C. Approximately one billionth of the total energy released by C. Approximately one billionth of the total energy released by
the sun strikes our atmospherethe sun strikes our atmospherei. Clouds, snow, ice, and the ocean reflect about 31% of i. Clouds, snow, ice, and the ocean reflect about 31% of the solar radiation that falls on Earththe solar radiation that falls on Earthii. Albedo is the proportional reflectance of solar energy ii. Albedo is the proportional reflectance of solar energy from the Earth’s surfacefrom the Earth’s surface
1. Glaciers and ice sheets have a high albedo and 1. Glaciers and ice sheets have a high albedo and reflect 80 to 90% of the sunlight hitting their reflect 80 to 90% of the sunlight hitting their
surfacessurfaces2. Asphalt pavement and buildings have a low 2. Asphalt pavement and buildings have a low
albedo albedo (10 to 15%)(10 to 15%)3. Forests have a low albedo (about 5%)3. Forests have a low albedo (about 5%)
iii. 69% of the solar radiation that falls on the Earth is iii. 69% of the solar radiation that falls on the Earth is absorbed and runs the hydrologic cycle, drives winds absorbed and runs the hydrologic cycle, drives winds and ocean currents, powers photosynthesis, and warms and ocean currents, powers photosynthesis, and warms the planetthe planet
Solar RadiationSolar Radiation
AlbedoAlbedo The reflectance of solar The reflectance of solar
energy off earth’s surfaceenergy off earth’s surface Dark colors = low albedoDark colors = low albedo
Forests and oceanForests and ocean Light colors = high albedoLight colors = high albedo
Ice capsIce caps
Sun provides energy for life, powers biogeochemical cycles, and determines climate
Not in Note packet
Temperature Changes with LatitudeTemperature Changes with Latitude
i. Near the equator, the sun’s rays hit i. Near the equator, the sun’s rays hit vertically vertically 1. Energy is more concentrated 1. Energy is more concentrated 2. Produces higher temperatures2. Produces higher temperatures3. Rays of light pass through a shallower 3. Rays of light pass through a shallower envelope of air envelope of air
Temperature Changes with LatitudeTemperature Changes with Latitude
ii. Near the poles, the sun’s rays hit more ii. Near the poles, the sun’s rays hit more obliquelyobliquely
1. Energy is spread over a larger surface 1. Energy is spread over a larger surface area (less concentrated)area (less concentrated)
2. Produces lower temperatures2. Produces lower temperatures
3. Rays of light pass through a deeper 3. Rays of light pass through a deeper envelope of air, causing the sun’s energy envelope of air, causing the sun’s energy to scatter and reflect back to spaceto scatter and reflect back to space
Temperature Changes with LatitudeTemperature Changes with Latitude
Equator (a)
High concentration Little Reflection High Temperature
Closer to Poles (c)
Low concentration Higher Reflection Low Temperature
From (a) to (c)
In diagram below
Temperature Changes with SeasonTemperature Changes with Season
Seasons Seasons determined by determined by earth’s tilt (23.5°)earth’s tilt (23.5°) ))
Causes each Causes each hemisphere to hemisphere to tilt toward the tilt toward the sun for half the sun for half the yearyear
Northern Hemisphere tilts towards the sun from March 21– September 22 (warm season)
The Atmosphere The Atmosphere
A. The atmosphere is an invisible layer of gases A. The atmosphere is an invisible layer of gases that envelops Earth and protects it’s surface that envelops Earth and protects it’s surface from lethal amounts of high energy radiation from lethal amounts of high energy radiation (i.e., UV rays, X rays and cosmic rays) (i.e., UV rays, X rays and cosmic rays)
i. 99% of dry air is composed of oxygen i. 99% of dry air is composed of oxygen (21%) and nitrogen (78%)(21%) and nitrogen (78%)
ii. Argon, carbon dioxide, neon, and helium ii. Argon, carbon dioxide, neon, and helium make up the remaining 1%make up the remaining 1%
The Atmosphere The Atmosphere B. The interaction between B. The interaction between
atmosphere and solar atmosphere and solar energy is responsible for energy is responsible for weather and climateweather and climate
C. Layers of the atmosphere C. Layers of the atmosphere vary in altitude and vary in altitude and temperature with latitude temperature with latitude and seasonand season
LAYERS OF THE ATMOSPHERE LAYERS OF THE ATMOSPHERE
i. Troposphere i. Troposphere 1. Closest layer to Earth’s surface1. Closest layer to Earth’s surface2. Temperature decreases with increasing altitude2. Temperature decreases with increasing altitude3. Extends to a height of approximately 10 km3. Extends to a height of approximately 10 km4. Weather, including turbulent wind, storms, and most 4. Weather, including turbulent wind, storms, and most
clouds occurs in the troposphereclouds occurs in the troposphere
ii. Stratosphereii. Stratosphere1. Temperature is more or less uniform, but does increase 1. Temperature is more or less uniform, but does increase
with increasing altitude with increasing altitude 2. Extends from 10 to 45 km above Earth's surface2. Extends from 10 to 45 km above Earth's surface3. Steady wind, but no turbulence (commercial jets fly 3. Steady wind, but no turbulence (commercial jets fly
here)here)4. Contains ozone layer4. Contains ozone layer
Diagram
LAYERS OF THE ATMOSPHERELAYERS OF THE ATMOSPHERE
iii. Mesosphereiii. Mesosphere1. Temperatures drop steadily (to lowest 1. Temperatures drop steadily (to lowest
temperature in atmosphere)temperature in atmosphere)
2. Extends from 45 to 80 km above Earth's 2. Extends from 45 to 80 km above Earth's surfacesurface
iv. Thermosphereiv. Thermosphere1. Very hot (nearly 1000˚C or more)1. Very hot (nearly 1000˚C or more)
2. Extends from 80 to 500 km2. Extends from 80 to 500 km
3. Aurora borealis occurs in this level of the 3. Aurora borealis occurs in this level of the atmosphereatmosphere
Diagram
LAYERS OF THE ATMOSPHERELAYERS OF THE ATMOSPHERE
v. Exospherev. Exosphere1. The outermost layer of the atmosphere1. The outermost layer of the atmosphere
2. Begins about 500 km above Earth's surface2. Begins about 500 km above Earth's surface
3. The exosphere continues to thin until it 3. The exosphere continues to thin until it converges with interplanetary spaceconverges with interplanetary space
Diagram
LAYERS OF THE LAYERS OF THE ATMOSPHEREATMOSPHERE
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Atmospheric CirculationAtmospheric Circulation
D. Differences in temperature caused by variations in D. Differences in temperature caused by variations in the amount of solar energy reaching different the amount of solar energy reaching different locations on Earth drive the circulation of the locations on Earth drive the circulation of the atmosphereatmospherei. Air is heated by warm surfaces near the equator i. Air is heated by warm surfaces near the equator cause it to rise and expandcause it to rise and expandii. Due to subsequent chilling, air tends to sink to the ii. Due to subsequent chilling, air tends to sink to the surface at about 30 degrees north and south surface at about 30 degrees north and south latitudeslatitudesiii. Similar upward movements of warm air and its iii. Similar upward movements of warm air and its subsequent flow toward the poles occur at higher subsequent flow toward the poles occur at higher latitudes, farther from the equatorlatitudes, farther from the equatoriv. This continuous turnover moderates iv. This continuous turnover moderates temperatures over Earth's surfacetemperatures over Earth's surface
Atmospheric CirculationAtmospheric Circulation
Surface windsSurface windsE. Surface windsE. Surface winds
i. Horizontal movements resulting from i. Horizontal movements resulting from differences in atmospheric pressure and from differences in atmospheric pressure and from the Earth's rotation are called windsthe Earth's rotation are called windsii. Winds tend to blow from areas of high ii. Winds tend to blow from areas of high atmospheric pressure to areas of low pressure atmospheric pressure to areas of low pressure (greater difference = stronger winds)(greater difference = stronger winds)iii. The influence of Earth's rotation, which iii. The influence of Earth's rotation, which tends to turn fluids (air and water) toward the tends to turn fluids (air and water) toward the right in the Northern Hemisphere and toward right in the Northern Hemisphere and toward the left in the Southern Hemisphere is called the left in the Southern Hemisphere is called the Coriolis effectthe Coriolis effect
Surface windsSurface windsiv. The atmosphere has three prevailing windsiv. The atmosphere has three prevailing winds
1. Polar easterlies blow from the northeast 1. Polar easterlies blow from the northeast near the North Pole or from the southeast near the North Pole or from the southeast near the South Polenear the South Pole2. Westerlies generally blow in the 2. Westerlies generally blow in the midlatitudes from the southwest in the midlatitudes from the southwest in the Northern Hemisphere or the northwest in the Northern Hemisphere or the northwest in the Southern HemisphereSouthern Hemisphere3. Trade winds (tropical winds) generally blow 3. Trade winds (tropical winds) generally blow from the northeast in the Northern from the northeast in the Northern Hemisphere or the southeast in the Southern Hemisphere or the southeast in the Southern HemisphereHemisphere
Surface windsSurface winds
The Global Ocean The Global Ocean
A. The global ocean is a single, continuous A. The global ocean is a single, continuous body of salt water that covers nearly ¾ of body of salt water that covers nearly ¾ of the Earth's surfacethe Earth's surface
B. Geographers divide it into four sections B. Geographers divide it into four sections separated by continents (Pacific, Atlantic, separated by continents (Pacific, Atlantic, Indian, and Arctic oceans)Indian, and Arctic oceans)
The Global OceanThe Global Ocean
The Global OceanThe Global Ocean
C. Prevailing winds blowing over the ocean's C. Prevailing winds blowing over the ocean's surface and the position of land masses surface and the position of land masses influence patterns of circulationinfluence patterns of circulation
i. Currents are mass movements of i. Currents are mass movements of surface-ocean watersurface-ocean water
ii. Gyres are large, circular ocean current ii. Gyres are large, circular ocean current systems that often encompass an entire systems that often encompass an entire ocean basinocean basin
iii. The Coriolis effect also influences the iii. The Coriolis effect also influences the paths of surface-ocean currentspaths of surface-ocean currents
Coriolis EffectCoriolis Effect
The Global OceanThe Global Ocean
B. The varying density of seawater affects B. The varying density of seawater affects deep-ocean currents and creates a deep-ocean currents and creates a vertical mixing of ocean watervertical mixing of ocean wateri. The ocean conveyor belt moves cold, i. The ocean conveyor belt moves cold, salty deep-sea water from higher to salty deep-sea water from higher to lower latitudes lower latitudes ii. The ocean conveyor belt affects ii. The ocean conveyor belt affects regional and possibly global climate and regional and possibly global climate and shifts from one equilibrium state to shifts from one equilibrium state to another in a relatively short period (years another in a relatively short period (years to decades)to decades)
The Global OceanThe Global Ocean
C. Ocean interactions with the atmosphere C. Ocean interactions with the atmosphere are partly responsible for climate variabilityare partly responsible for climate variability
El Niño-Southern Oscillation El Niño-Southern Oscillation (ENSO)(ENSO)
El Niño-Southern Oscillation El Niño-Southern Oscillation (ENSO) (ENSO)
i. ENSO - is a periodic, large scale warming of i. ENSO - is a periodic, large scale warming of surface waters of the tropical eastern Pacific surface waters of the tropical eastern Pacific Ocean that temporarily alters both ocean and Ocean that temporarily alters both ocean and atmospheric circulation patternsatmospheric circulation patterns
1. Most ENSOs last 1 to 2 years1. Most ENSOs last 1 to 2 years
2. ENSO has a devastating effect on fisheries 2. ENSO has a devastating effect on fisheries off South America and alters global air currents off South America and alters global air currents (causing severe and unusual weather (causing severe and unusual weather worldwide)worldwide)
La NiñaLa Niña
ii. ii. La Niña occurs when the surface La Niña occurs when the surface water temperature in the eastern Pacific water temperature in the eastern Pacific Ocean becomes unusually cool, and Ocean becomes unusually cool, and westbound trade winds become unusually westbound trade winds become unusually strongstrong1. La Nina often occurs after an ENSO1. La Nina often occurs after an ENSO
2. La Nina also affects weather patterns around 2. La Nina also affects weather patterns around the world, but its effects are more difficult to the world, but its effects are more difficult to predictpredict
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Weather and Climate Weather and Climate
A. WeatherA. Weatheri. Weather refers to the conditions in the i. Weather refers to the conditions in the
atmosphere at a given place and timeatmosphere at a given place and time
ii. Weather includes temperature, atmospheric ii. Weather includes temperature, atmospheric pressure, precipitation, cloudiness, humidity, pressure, precipitation, cloudiness, humidity, and windand wind
iii. Weather is continuously changing (hour iii. Weather is continuously changing (hour to hour, day to day)to hour, day to day)
Weather and Climate Weather and Climate
B. ClimateB. Climatei. The average weather conditions that i. The average weather conditions that occur in a place over a period of years is occur in a place over a period of years is termed climatetermed climateii. Climate is determined by temperature ii. Climate is determined by temperature and precipitationand precipitationiii. Other climate factors include wind, iii. Other climate factors include wind, humidity, fog, cloud cover, and humidity, fog, cloud cover, and occasionally lightningoccasionally lightning
Weather and Climate Weather and Climate
C. Precipitation C. Precipitation
i. Precipitation refers to any form of i. Precipitation refers to any form of water that falls from the atmospherewater that falls from the atmosphere
ii. Examples of precipitation include rain, ii. Examples of precipitation include rain, snow sleet and hailsnow sleet and hail
iii. Precipitation has a profound effect on iii. Precipitation has a profound effect on the distribution and kinds of organisms the distribution and kinds of organisms presentpresent
Weather and ClimateWeather and Climate
D. Rain shadows, tornadoes and tropical D. Rain shadows, tornadoes and tropical cyclones (hurricanes/typhoons) are cyclones (hurricanes/typhoons) are extreme forms of weather that can have extreme forms of weather that can have a significant impact on regional climate a significant impact on regional climate
Internal Planetary Processes Internal Planetary Processes
A. Plate tectonics A. Plate tectonics i. Plate tectonics is the study of the dynamics of Earth’s i. Plate tectonics is the study of the dynamics of Earth’s
lithosphere (outermost rigid rock layer)lithosphere (outermost rigid rock layer)
1. The lithosphere is composed of seven 1. The lithosphere is composed of seven large plates, plus a few smaller oneslarge plates, plus a few smaller ones
2. The plates float on the asthenosphere 2. The plates float on the asthenosphere (the (the region of the mantle where rocks region of the mantle where rocks become hot become hot and soft) and soft)
ii. Plate boundaries are typically sites of intense ii. Plate boundaries are typically sites of intense geologic activity – earthquakes and geologic activity – earthquakes and
volcanoes are common in such a regionvolcanoes are common in such a region
Internal Planetary ProcessesInternal Planetary ProcessesB. EarthquakesB. Earthquakes
i. Forces inside Earth sometimes push and stretch rocks i. Forces inside Earth sometimes push and stretch rocks in the lithospherein the lithosphere
1. The energy is released as seismic waves causing 1. The energy is released as seismic waves causing earthquakesearthquakes
2. Most earthquakes occur along fault zones2. Most earthquakes occur along fault zones3. More than 1 million earthquakes are recorded each year3. More than 1 million earthquakes are recorded each year
ii. Landslides and tsunamis are some of the ii. Landslides and tsunamis are some of the side effects of earthquakesside effects of earthquakes
C. VolcanoesC. Volcanoesi. When one plate slides under or away from an i. When one plate slides under or away from an
adjacent plate, magma may rise to the surface, adjacent plate, magma may rise to the surface, forming a volcanoforming a volcano
ii. Volcanoes occur at subduction zones, spreading ii. Volcanoes occur at subduction zones, spreading centers, and above hot spotscenters, and above hot spots